This invention relates to jars utilized in well bores. More particularly, but not by way of limitation, this invention relates to an auto set hi-directional jar that provides both an upward and downward jarring action to a mass in a well bore. After permitting the jarring of the mass, the apparatus of the present invention will be automatically positioned to provide a reciprocating jarring action.
In the drilling, completion or re-completion of a well, many times the operating string becomes lodged in the well bore. Once the string is lodged, or stuck as is commonly referred to those of ordinary skill in the art, the operator will require that the lodged object be freed. This process of freeing the stuck object is known as fishing.
Many different types of prior art devices have been utilized in the industry. Generally, these jars employ a moving mass impacting a stationary anvil. One of the first jarring devices can be seen in U. S. Pat. No. 2,122,751 to Kennedy. Another jar of the type utilizing a moving mass impacting an anvil can be seen in U. S. Pat. No. 2,122,751 to Phipps. Yet another jar is seen in U. S. Pat. No. 4,333,542 to Taylor. In U. S. Pat. No. 4,688,649 to Buck, the invention discloses a latching device utilized with a down hole jar.
In U. S. Pat. No. 5,139,086 by Griffith, the specification discloses a combined accelerator and jar for sudden release of accumulated energy, for delivering an up or down jarring impact. In this patent to Griffith, one of the problems solved by the invention over the prior art was the allowing of a jarring impact in either an upward or downward direction. Nevertheless, the operator must still "re-set" the jar in order to place the jar in a position to jar. All of the prior art jars share this difficulty of having to re-set the jar in order to impact the hammer on the anvil. This invention solves this problem by having a self-operating re-set design such that the jar, after firing, is automatically re-set.